72785821 has 4 divisors (see below), whose sum is σ = 73309600. Its totient is φ = 72262044.

The previous prime is 72785809. The next prime is 72785831. The reversal of 72785821 is 12858727.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 72785821 - 2⁹ = 72785309 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (72785831) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 261681 + ... + 261958.

It is an arithmetic number, because the mean of its divisors is an integer number (18327400).

Almost surely, 2^72785821 is an apocalyptic number.

It is an amenable number.

72785821 is a deficient number, since it is larger than the sum of its proper divisors (523779).

72785821 is a wasteful number, since it uses less digits than its factorization.

72785821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 523778.

The product of its digits is 62720, while the sum is 40.

The square root of 72785821 is about 8531.4606604028. The cubic root of 72785821 is about 417.5247856011.

The spelling of 72785821 in words is "seventy-two million, seven hundred eighty-five thousand, eight hundred twenty-one".